Gunther Holtorf and his wife Christine on a 500,000 mile journey around the world

The Son Doong Cave in Vietnam is the biggest cave in the world. It's over 5.5 miles long, has a jungle and river, and could fit a 40-story skyscraper within its walls.

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If you're planning a trip, check out these standout sites to get the best deal possible on your flight.

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Trademark Fine Art Typography World Map III by Michael Tompsett Canvas Wall Art, 22x32-Inch by Trademark Fine Art, http://www.amazon.com/dp/B009VXKAKC/ref=cm_sw_r_pi_dp_hD30rb1HVAE2Z

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THE DREAM! - How to drive across the USA hitting all the major landmarks. 12,225 miles. Click to see time-lapse drive across America in 5 minutes, hitting major landmarks.http://www.picturecorrect.com/news/time-lapse-drive-across-america-in-5-minutes/

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Starfish Beach, Grand Cayman

I will travel the world....checking 'em off the list!

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Awesomeness from places around the world

Explore the caves of Hang Son Doong, Vietnam, part of a network of over 150 caves. Surrounded by jungle and used in the Vietnam war as a hideout from American bombardments, the cave passage is so large that it could hold a block of 40-storey skyscrapers.

car camping

Road trip to Joshua Tree National Park, California #JoshuaTree #JoshuaTreeNationalPark #California #Desert #SoCal

World's deepest indoor diving pool, Belgium

Krubera Cave (deepest cave in the world) in the Western Caucasus